Pelikan revised piston fillers - P1 and other models

In September 1958 Pelikan introduced the first of a new generation of fountain pens that had been completely redeveloped in construction and design. The shape was slimmer than previous fountain pens. The piston mechanism had remained unchanged technically. But the key was the new ink feed. Developed by Theodor Kovacs and called the 'Pelikan thermic-regulator', it had a significantly larger volume for storing remaining ink. Atmospheric pressure and temperature variations were no longer a problem. In addition, this new development now also allowed the installation of a hooded nib.

The P1 initially had screw caps; later developed piston fillers had only push-fit caps, until the 1980s.

The first model (September 1958 until March 1959) has a clutch ring on the barrel, the later model until 1963 had the clutch ring hidden in the cap.

From 1958-1962, the cap engraving was a single line. In the last production period (1962-1963) the cap was engraved with two lines.

The picture below shows the two different grip sections, one with flattened edges (used 1959 and 1960) and one without. So far we have not been able to identify further details of the relationship between the section styles and production timeline.

Changing the nib or unscrewing the ink feed was only possible with a special tool, which can be seen in the photos below.

Weight	Total Length	Barrel Length	Cap Length	Diameter	Ink Capacity
0.51 oz	5.20 in	4.84 in	2.40 in	0.43 in	1.5 ml
14.6 g	132 mm	123 mm	61 mm	11 mm

All fountain pens with the new half covered nib have now no screw cap, but feature a plug cap. They all feature a revolving window that shows the level of ink. As a further feature every fountain pen has a wide metal ring at the transition from the grip section to the ink window.
Rules of the model name: The model number starts with Mxx or MKxx. The M stands for filler with mechanics (ie piston filler). The models Mxx have a metal cap, either made of nickel silver (Silvexa) or gilt nickel silver (gold Doublé). The model numbers MKxx denote the less expensive models with plastic cap (K = plastic in german "Kunststoff").
In two exceptional cases, these rules differ: the Model MK10 black / green is as identical model called 120 black / green. The model MK30 is black also known as identical model under the name M25 black.

M10 and MK10 have a stylized beak clip.

Weight	Total Length	Barrel Length	Cap Length	Diameter	Ink Capacity
MK10: 0.44 oz	5.24 in	4.53 in	2.44 in	0.43 in	1.1 ml
MK10: 12.4 g	133 mm	115 mm	62 mm	11 mm

With the redesign and development of the new nib style some of the old models run out, others are replaced by successor models. All models have in addition to the new nib style now a narrow ring between the grip section and the ink window.

Weight	Total Length	Barrel Length	Cap Length	Diameter	Ink Capacity
	5.24 in	4.53 in	2.44-2.48 in	0.43 in	1.1 ml
	133 mm	115 mm	62-63 mm	11 mm

The demand for Deskpens was great in some countries, so Pelikan let produce the models MK10 and MK30 with an elongated, non-removable knob for export in the version as Deskpen.
1973 replaced the new Pelikan model M480 the model MK10 with minor changes. The bar-clip has broadened, the gold ring between grip and ink window is narrow, the feed and the nib unit are adjusted according to the time. Similarly, there is now an export version of the variant M480S green as a Deskpen to replace the Deskpen model M10S.

Weight	Total Length	Barrel Length	Cap Length	Diameter	Ink Capacity
0.37 oz	6,77 in	4.02 in	2.28 in	0.43 in	1.1 ml
10.5 g	172 mm	102 mm	58 mm	11 mm